This invention relates to an apparatus for detecting metal debris particles in a fluid flowing in machinery, for example a lubricant oil system in rotating or reciprocating machinery.
Investigations have shown that in machinery, for example rotating and reciprocating machinery such as engines, turbines, pumps, gearboxes, compressors and the like, when abnormal conditions develop in oil wetted components, the amount and size of oil transported metallic debris increases.
The early detection of these changes is essential in the prevention of rapid machine degradation and/or unscheduled stoppages resulting from machine or component failure.
Various techniques to detect circulating metal debris particles have been investigated. One of these known techniques is the use of the commercially produced "Grid Switch" particle detector as described in U.K. Patent Specification No. 1,256,291. This detector is a simple device for detecting large metal debris particles circulating in lubricant systems. Oil flows continuously through a perforated element or grid covered with a printed circuit comprising two interposed electrically conductive strips, which communicate with a relay. When a particle or particles of metal debris large enough to bridge the gap between two strips is/are trapped on the element, the relay operates and may trigger an alarm system or switch off the machinery. When an alarm is triggered the grid can be observed visually, if desired.
However, this known device is a single switch which once activated will not respond to other particles bridging the gaps between the two strips. Further, this known device is restricted to the detection of debris in oil only.
These and other limitations and disadvantages of the prior art are overcome by the present invention however, and an improved apparatus for detecting metal particles in a fluid is provided.